German Offenlegungsschrift 3,611,063 discloses a saw blade with teeth which are provided in recurring cycles. Each cycle thereby forms at the same time a group of teeth, so that the number of teeth per cycle coincides with the number of teeth per group. The teeth in the group or in the cycle are differentiated with regard to a leading tooth, that is the first tooth, in a cycle or group and with regard to following teeth. The leading tooth in this case has the greatest height and the tooth height decreases in the group. The following teeth are formed as set teeth and are generally provided alternately set to left and right, in order in this way to make the width of the cut channel greater than the width of the basic body of the saw blade. Instead of only one unset leading tooth, two unset leading teeth may also be provided in front of the set following teeth, it being possible to form the first leading tooth externally with two phases and to this extent make it symmetrical with respect to a longitudinal center plane of the basic body. In conjunction with a height offset, the two leading teeth are in this way shaped similarly to the known roughing tooth and finishing tooth of a circular saw blade and the effective cutting edge of the one leading tooth is in this case divided in the known way between two leading teeth. The width of the two leading teeth in this case coincides with the width of the basic body. Consequently, necessarily set following teeth are provided thereafter in the group or in the cycle. In a further group of teeth, three unset leading teeth and two set following teeth are combined, the effective cutting edges or cutting-edge sections of the leading teeth being divided by phases on the first and second leading teeth between the three leading teeth. The leading teeth are also graduated decreasingly in height, just like the adjoining set following teeth. All the leading teeth have a width which does not exceed the width of the basic body of the saw blade. Therefore, set following teeth are also always provided. However, in German Offenlegungsschrift 3,611,063 there is also described an illustrative embodiment in which no set teeth but only unset teeth are provided in the group of teeth or in the recurring cycle. The present invention is based on such a saw blade. A leading tooth is followed by two following teeth, giving a height decreasing from tooth to tooth and a width increasing from tooth to tooth in the group. All the teeth are formed symmetrically with respect to a longitudinal center plane through the basic body. The first tooth in the group of teeth has a cutting edge which is formed in a continuous straight line, this cutting edge extending perpendicularly with respect to the longitudinal center plane of the saw blade. This first tooth coincides in its width with the width of the basic body. The two following teeth likewise have cutting edges which are in a continuous straight line perpendicularly with respect to the longitudinal center plane but of which in each case only outer parts are effective. The following teeth have different flank angles and, although the enclosed angle between flank and cutting edge is different on the individual following teeth, it is always formed as an acute angle. The effective cutting edge increases in its length from tooth to tooth in the group, so that the major cutting work is to be performed by the leading tooth, and the two following teeth essentially effect only a widening of the cut channel in order that a clearance cut is achieved. This illustrative embodiment of a saw blade is intended to coincide in function and effect with the illustrative embodiments in which set teeth are used. Such a saw blade in which the teeth are formed symmetrically with respect to a longitudinal center plane through the basic body, only unset teeth being used, is extremely elaborate in production, it not being clear how the greater width of the following teeth, in comparison with the width of the basic body, is to be achieved in the first place. In addition, this embodiment with the unset teeth also has numerous other disadvantages. The effective part of the cutting edge on the following teeth in each case encloses an acute angle with the flank, that is an angle which is less than 90.degree., so that when cutting work is performed these lateral tooth tips are subjected to wear, by which the width of the cut channel decreases rapidly. This disadvantage does not occur to such a great extent on the set teeth, since here the angle between effective cutting edge and flank is approximately 90.degree.. Set following teeth are always unfavorable for the straight running of a saw blade, because lateral forces occur on them, that is forces which, acting on one side, result in a deflection of the set tooth concerned. This has an effect not only with regard to a poorer surface quality on the cut face in the cut channel, but at the same time constitutes an excitation of vibrations for the saw blade. The unset leading tooth has no lateral clearance angle, so that it rubs in the guide channel in the region of its flanks. The leading tooth must perform the main cutting work and thereby clear the greatest cross section. This also applies to a plurality of leading teeth within a group of teeth; in all cases, the set teeth are loaded less. Due to the alternate arrangement of set teeth, there is the risk of the outer corners of the teeth set laterally to the right exhibiting different wear than the outer corners of the teeth set laterally to the left. This wear is the cause or the beginning of a tendency of the saw blade to run sideways.
Also known is a saw blade designed as a band saw blade, in which, to simulate a roughing tooth and finishing tooth on circular saw blades, the effective cutting edge is divided over the cut channel width between the roughing tooth and finishing tooth. The roughing tooth has a greater tooth height than the finishing tooth. The finishing tooth, however, has a greater tooth width than the roughing tooth. The effective parts, that is the cutting parts of the respectively provided tooth cutting edge, are formed on the roughing tooth and finishing tooth by a jutting-out cutting edge, there being provided externally in each case a phase which is inclined toward the basic body. The roughing tooth and finishing tooth in the group of teeth have an angle formed between the phase and the flank so as to be greater than 90.degree.. Consequently, the finishing tooth is less sensitive to wear in the region of its corners between phase and flank, cutting the side wall of the cut channel, than in the case of an acute-angled configuration. However, this design is restricted to two teeth in the group as the roughing tooth and the finishing tooth and, by the small number of teeth in the group, is aimed at removing the thinnest possible chips during cutting.